1. Field of the Invention
The present invention relates to a gas turbine engines of the type having sequential combustion.
2. Discussion of Background
In gas turbines having sequential combustion, as has been disclosed by U.S. Pat. No. 5,577,378, a fuel/air mixture is burned in a first combustion chamber and is then fed to a second combustion stage after an expansion in a first turbine.
The velocity profile of the flow leaving the impeller of the first turbine is intensely swirled in such a way that this flow has to be rectified in order to ensure an optimum incident flow to the following mixing elements belonging to the second combustion chamber, so that as far as possible intimate mixing of these partly expanded hot gases with the fuel fed into the second combustion chamber is achieved, taking as a basis the fact that the second combustion chamber is operated according to a self-ignition process, so that particular importance has to be attached there to optimum mixing for maximizing the efficiency and for minimizing the pollutant emissions.
The quality of the intimate mixing of the fuel injected into the second combustion chamber is in principle dependent the turbulence caused by the mixing elements on the flow of the partly expanded hot gases, i.e. the mixing elements are designed in such a way that they can provide the vortex flow which offers the best preconditions for optimum mixing and combustion. However, this requires the mixing elements to be subjected to an irrotational incident flow over the entire cross section of flow, which an irrotational incident flow, however, is not present downstream of the first turbine for the reasons mentioned.